Surveying instrument including guide light irradiation unit

A surveying instrument comprising:

• a surveying instrument main body made up of a base portion and a rotating pedestal to be rotated horizontally with respect to the base portion;
• a guide light irradiation unit configured to irradiate guide light to indicate a collimation direction of the surveying instrument main body to a survey operator;
• and
• a cover member, in which on the rotating pedestal, a support member by which a lens barrel portion of a distance-measuring optical system is vertically rotatably supported is provided, and the cover member covers the surveying instrument main body including the support member and the lens barrel portion and covers the guide light irradiation unit, wherein
• the guide light consists of light differing in pattern between the left and the right of an optical axis center of the guide light irradiation unit,
• the guide light irradiation unit is horizontally shifted with respect to the lens barrel portion and held by the support member so that an optical axis of the guide light irradiation unit becomes substantially parallel to an optical axis of the lens barrel portion in the horizontal direction, and
• a horizontal shift distance D between the optical axis of the guide light irradiation unit and the optical axis of the lens barrel portion satisfies:
• tan(α/2)×Cmin>D
• provided that α is an irradiation angle of the guide light in the horizontal direction, and Cmin is a shortest use distance of the surveying instrument.